Muffler construction



March 20, 1934. 1 s w so 1,951,8 3

MUFFLER CONSTRUCTION Filed Sept. 18, 1951 Z II- .1

Inventor, Irving ,5. Hatsan,

P w /f A ttorney.

Patented Mar. 20, 1934 UNITED STATES PATENT OFFICE MUFFLER CONSTRUCTION Application September 18, 1931, Serial No. 563,546

6 Claims.

In this specification, and the accompanying drawing, I shall describe and show a preferred form of my invention, and specifically mention certain of its more important objects. I do not limit myself to the forms disclosed, since various changes and adaptations may be made therein without departing from the essence of my invention as hereinafter claimed; and objects and advantages, other than those specifically men 10 tioned, are included within its scope.

This invention relates to mufiler construction for silencing the exhaust from internal combustion engines. Among its more important objects are: first, to provide a device of this nature that is adapted for insertion into existing exhaust pipes of internal combustion engines; second, to pro- Vide a muflier construction wherein the proportions of its constituent elements may easily be varied throughout wide ranges, to adapt the device to meet a great variety of operating conditions, without departing from its essential inherent characteristics; third, to provide an exhaust muffler wherein there are no dead-end flow passages, and wherein no reversals of flow direction are required; fourth, to provide a muffler construction wherein the so-called back pressure effect is relatively small and easily controllable; and, fifth, to accomplish the above objects by means of a very simple and relatively inexpensive construction.

- struction, taken on the line 2-2 of Fig. 1; and

Figure 3 is a plan View of the prepared material of which the flow-control portion of the muffler is constructed.

The figures are to be regarded as being some- What diagrammatic, rather than strictly pictorial. Similar reference numerals refer to similar parts throughout the several views.

The purpose of exhaust mufflers is to flatten out the sharp periodic peaks of exhaust pressure, so as to obtain a much greater uniformity of velocity of the exhaust gases than would otherwise occur. To accomplish this, it is usually desirable to introduce a flow resistance that is quite small at low gas velocities, and very much great-- 5 er at high velocities. It is also desirable to take advantage of all possible sources of heat radiation, for the purpose of cooling the exhaust gases quickly, and thereby reducing their volume. Both of these general means for accomplishing the desired purpose, have been utilized in my improved construction.

In my muffler I introduce great resistance to the flow of gases at high velocity by means of alternately increasing and decreasing the areas of the flow passages in rapid succession; and by breaking up the flow of the gases into many minute currents in slightly diverging directions, which necessarily impinge upon each other. Obviously, this introduces a very great flow resistance to gases at high velocity, and offers very slight resistance to gases at low velocity.

The available heat radiating surface of all mufflers is necessarily that of their enclosing shells; and, in order to take advantage of such radiation to the fullest extent, it is desirable to give the gases a rotative tendency that will cause them to impinge upon the inner walls of the shells. I utilize this principle also, in my improved construction.

For the flow-control portion of my muffler, I prefer to employ a specially prepared sheet of wire-mesh fabric that has relatively large square shaped meshes between the wires, such as is indicated generally at 6. On one side of the fabric I place a series of spaced diagonal strips or Wires '7, usually of a thickness or diameter, as the case' may be, considerably greater than the diameter of the wires 8 that compose the fabric. These spacing strips or wires are so arranged that the opposed extremities of adjacent strips, transversely across the fabric, over-lap each other with respect to the longitudinal direction of the fabric. Thus extremities 9 and 10 are not directly opposite each other across the fabric, and extremity 9 is nearer the bottom thereof than is extremity 10. The spacing strips should be attached to the mesh in a permanent way, as by welding them to the fabric at frequent intervals along their length.

Having thus prepared the material for the flow-control portion of the mufiler, the fabric sheet is rolled up in the form of a spiral, as illustrated in Figs. 1 and 2. In this rolling, the spacing strips will take a helical form, and serve to space the successive layers of the roll from each other. They will thus provide unobstructed helical flow passages between the layers of the spirally wound fabric. The described overlapping of the ends of the spacing strips will greatly facilitate rolling the prepared sheet; and this, in fact, is the main purpose of the arrangement. Still greater facility in rolling may be attained, if flexible stranded wire cables are used for the spacers '7.

The specially prepared fabric, formed into a spiral roll in the manner described, may be introduced into any suitable form of tubular casing, to constitute a very efiective muffler for the exhaust of internal combustion engines. The roll must, of course, be retained within such casing, and the casing be furnished with inlet and outlet means for the gases, in ways that will be readily understood by those familiar with such constructions.

In addition to the above use, and greatly extending the utility of the device, the roll readily permits itself to be made into a cartridge that is adapted for being inserted directly into the extremity of an exhaust pipe. In such use the pipe will cooperate with the roll, in the same manner as the casing mentioned above. This is the embodiment of my invention that I have selected for illustration in Figs. 1 and 2.

For the purpose of forming the roll into a cartridge that is adapted for direct insertion in an exhaust pipe, I surround each end of the rolled fabric with a metallic ferrule. I prefer to make these of resilient material, and in the respective forms shown at 11 and 12. These ferrules are of slightly less diameter than exhaust pipe 13, into which the cartridge is to be inserted, and they should be firmly attached to the fabric roll in some convenient manner. This can be accomplished by welding, or by pressing partially severed V-shaped points 14 inwardly from the ferrules, in such a way as to engage some of the mesh wires of the fabric as indicated at 15. Means should also be provided to keep the cartridge from chattering within the exhaust pipe, and for retaining it therein against the expelling force of the exhaust ases.

In order to center the cartridge within the exhaust pipe, and at the same time to effectively prevent it from chattering, I prefer to form the ferrules with a plurality of angularly spaced integral fingers 16, pressed outwardly from the material of the ferrules by severing the fingers therefrom on three sides as indicated. The free extremities of these fingers will extend beyond the periphery of the ferrules so that, when the cartridge is pushed into an exhaust pipe, the fingers will resiliently engage the walls of the pipe. This will effectively center the device, and also prevent chattering thereof.

For retaining the cartridge within the exhaust pipe, against the expelling force of the gases, I prefer to provide holes 1'? at the free extremity of the fingers of the outer ferrule. Stove-bolts 18 may then be passed through these holes from the inside, and through correspondingly positioned holes drilled in the exhaust pipe, and the cartridge may then be firmly secured in place by nuts 19.

From the foregoing description it will be apparent that I have provided a mufiler having a multiplicity of unobstructed helical fiow passages from end to end of the device, formed by the helical spacing strips and the adjacent spaced layers of the fabric. Although unobstructed, these passages will introduce a great flow resistance to gases at high velocities, by reason of the meshes in the fabric. These mesh spaces act to alternately decrease and enlarge the cross-sectional area of the flow passages in rapidly recurring frequency, and at a large number of points. It is well known that such construction will introduce great flow resistance to gases at high velocity, and very little flow resistance to gases at low velocity. It will be noted moreover, that the adjacent helical flow passages of the muffler, radially speaking, are in communication with each other through the meshes of the fabric. Obviously therefore, the flow currents will impinge upon the circumferential wires of the fabric, at a great number of places. The flow will thus be broken up into a multiplicity of small currents, taking diagonal directions with respect to the axis of the muffler. These small currents will impinge upon each other and introduce a further resistance to the flow of the gases at high velocity, and have little effect upon the flow at low velocity.

For both of the reasons just mentioned, the pressure peaks of the exhaust will be greatly flattened out, and the operating result will be a comparatively uniform and low velocity of the gases where they emerge from the muffler.

I desire to call attention to the fact that the diagonal placing of spacing strips 7 on the wire mesh fabric, not only results in making it easier to form a roll thereof; but, by reason of the helical flow passages formed by the aid of the spacing strips, the gases will have a rotary impulse imparted to them, tending to cause them to work outwardly against the shell of the muffler, and thus take advantage of the radiating surface that such shell affords. The gases will be cooled by such radiation, be reduced in volume thereby, and make it possible to reduce the dimensions of the muflller in proportion to the amount of such radiation.

It will be apparent that my construction lends itself very readily to varying the proportions of the elements, to meet various operating conditions. Thus the length of the muffler is controlled by the width of the fabric from which the roll is formed. The diameter of the roll depends simply upon a number of layers. The effective number of expansions and contractions in the helical flow passages may be controlled by the size of the meshes in the fabric constituting the roll.

Finally, I desire to emphasize the great simplicity of the construction, its relative cheapness, its adaptability for utilizing the exhaust pipe itself as the shell of the muffier, and the fact that there are no dead ends in the flow passages requiring a reversal of flow of the exhaust gases.

Having thus fully described my invention, I claim:

1. A mufiler comprising; a spirally wound roll of metallic mesh fabric having its layers spaced by helically disposed strips forming helical flow passages between the layers; and a cylindrical coaxial shell surrounding the roll, adapted for directing a longitudinal gas flow therethrough into said passages.

2. A mufiler comprising; a roll of metallic mesh fabric having its layers spaced by helically disposed strips, and inserted co-axially into a cylindrical shell; and a ferrule surrounding an end of said roll, attached thereto and to the wall of said shell; said shell being adapted for directing a longitudinal gas flow therethrough into the helical passages formed by said strips.

3. A mufiler comprising; a spirally wound roll of metallic mesh fabric having its layers spaced by strips forming helical flow passages between the layers, inserted co-axially into a cylindrical shell; and a ferrule surrounding an end of said roll and attached thereto; said ferrule being provided with means for centering the roll within, and attaching it to, the wall of said shell; and said shell being adapted for directing a longitudinal gas flow therethrough into said helical flow passages.

4. A muflier comprising; a roll of wire mesh fabric having its layers spaced by helically disposed strips; a co-axial cylindrical shell surrounding said roll; and ferrules of resilient metal surrounding the respective ends of said roll and attached thereto; said ferrules being provided with integral resilient fingers extending beyond the peripheries of the ferrules, centering said roll within said shell; at least one of said fingers being attached to the wall of said shell; and said shell being adapted for directing a longitudinal gas flow therethrough into the helical passages formed by said strips.

5. A mufiler comprising; a spirally wound roll, formed of wire mesh fabric having parallel spaced diagonal metal strips attached thereto, whereby the layers of the wound fabric are spaced; a coaxial cylindrical shell surrounding said roll; and ferrules of resilient metal surrounding the respective ends of said roll and attached thereto; said ferrules being provided with angularly spaced integral fingers, partially severed therefrom and having free extremities extending outwardly from the ferrules, whereby said roll is centered within said shell and attached thereto; and said shell being adapted for directing a longitudinal gas flow therethrough into the helical passages formed by said strips.

6. The construction set forth in claim 5, Wherein the opposed ends of adjacent spacing strips, considered transversely of the fabric before it is Wound into the roll, are in overlapping relation with respect to their longitudinal positions upon the fabric.

IRVING S. WATSON. 

